The invention is an invertible catamaran vessel which, in its upright, yacht tender mode, may be propelled by sail, outboard motor, or by rowing. In its inverted mode, the vessel offers outstanding functional advantages as well as improved safety and convenience for swimmers, SCUBA divers, etc.
Getting on board a boat from the water, in some cases with heavy equipment, can be clumsy, fatiguing, dangerous, and at times impossible to do without assistance. Heretofore, there have been four basic ways of boarding a boat from the water, namely, (1) without aid; (2) swim steps; (3) a ladder; and (4) a ramp.
The use of muscle power alone to get over the side of a boat is by far the most difficult and dangerous of the abovementioned techniques. This method requires a great deal of upper body strength and may not be possible with SCUBA equipment, or when entering a boat with over 12 inches of freeboard. A fatigued swimmer has no means of resting and regaining his or her strength. The time required by this method of exiting the water may leave swimmers vulnerable to attack by sharks or other marine predators.
Swim steps are usually mounted about a foot or more above the water line, and usually extend a maximum of 24 inches beyond the transom. They require balance and upper body strength similar to unaided boarding, and share all of the disadvantages of unaided boarding.
As to the use of ladders, they do offer some improvement over unaided boarding. These devices can also be used in conjunction with a swim step. Ladders still require balance and upper body strength. The receding curvature of most boat hulls further increases the difficulty and danger of this boarding method. The ladder at best provides a very poor resting area for fatigued swimmers. Divers may become very vulnerable to currents since they must remove their fins in order to negotiate the steps of the ladder. Also, ladders are usually unstable, difficult and slow to use.
Diving ramps are used on commercial SCUBA diving boats. They are usually constructed of porous stainless steel and wood platforms approximately 8 feet square. These platforms are attached to the transom of the boat at a point one foot or more above the water line. The opposite end of the platform can be lowered to a point one foot or more below the surface of the water. This method of boarding is easy, rapid, safe, and requires very little upper body strength. The ramp provides a zone of transition for swimmers that functions much like the shallow end of a swimming pool where the swimmer or diver can take advantage of both the buoyancy of the water and the solid structural support of the ramp. Fatigued swimmers can "beach" themselves with very minimal effort and regain their strength until they are able to complete the boarding process. The ramp offers a convenient place for the SCUBA diver to remove bulky equipment while it is partially supported by it's own buoyancy. The speed of this boarding method, along with the structure of the ramp may also provide some protection from marine predators.
The diver's ramp, however, is not without problems. It is expensive, ungainly, and difficult to mount and maintain. Ramps are especially unsuited to boats with narrow transoms, such as sail boats, or boats with protrusions, such as rudders or stern drives. Few boat owners would wish to spoil the aesthetics of their craft with such unsightly structures.
In contradistinction to the prior art, the present invention is an aesthetic and ultra-functional solution to the problems raised with the four traditional boarding methods. The invention fulfills two separate and necessary rolls for the larger boat owner in it's compact package which can be easily disassembled for storage aboard the larger craft. In it's upright position, the invention is an economical, convenient, safe, and super stable yacht tender which can greatly ease the task of transporting passengers from boat to dock, boat to boat, or boat to shore. In it's inverted position, the invention becomes an extraordinary boarding device that functions much like a dive ramp with a submerged safety zone portion, and with the additional advantage that it can be placed to allow access at any point along the primary craft's hull. For example, it can be tethered close to the primary vessel by use of suction cups which attach to the hull of the primary craft, the suction cups being attached to it by short lanyards. Of course, the invention can be positioned completely independently from the primary craft and used as a swimming or divers float.
In reviewing the patented prior art, an improvement in life rafts, particularly of a reversible and collapsible type was found in U.S. Pat. No. 1,104,845. This device includes a valve mechanism for automatically venting the water from the raft in either of its positions. In U.S. Pat. No. 1,973,584, there is described an improvement in rafts for swimming and diving purposes which includes a submersible ladder or ladders suspended below a fabric cover stretched between two elongated tubes or containers (floats). In still another example of the prior art, in U.S. Pat. No. 3,048,859, a raft is shown that includes stabilization means, including a pair of elongated frusto-conical members, which considerably diminishes tilting and practically prevents overturning of the raft under unequally distributed load and under the action of waves. However, in none of the above referenced prior art patents is there described the simple yet advantageous structure of the present invention which includes a submersible safety zone portion in its inverted configuration.
It should thus be clear that the prior art in the subject area of interest generally lacks the utility, helpfulness, simplicity, ruggedness, and safety that is most desired in a combination tender/boarding vessel, and that a vessel which obviates the aforementioned shortcomings would constitute a significant advancement in the art.